Analysis of peroxidase negative acute leukemias by monoclonal antibodies: III. Acute lymphoblastic leukemia.

Peripheral-blood leukemic cells from 45 patients with peroxidase negative acute lymphoblastic leukemia (ALL), which did not express either myeloid or megakaryocyte-platelet-related cell surface antigens, were analyzed by using monoclonal antibodies capable of recognizing T- or B-cell-associated and/or T- or B-cell-restricted antigens. Numerous subclasses of ALL, including B-cell lineage leukemias and T-cell lineage leukemias, were identified phenotypically and immunophenotypically in an effort to more accurately characterize the heterogeneous ALLs, their states of differentiation, and their relationships to normal B- and T-lymphoid cells. Among the cases studied, only seven (15.6%) were found to have stem cell (undifferentiated) leukemia (Ia+, CD24+, CD9+, CD34+). It is concluded that the use of monoclonal antibodies for the characterization of heterogeneous ALLs improves the specificity of leukemia classification, which may contribute to the selection of more effective forms of therapy for the types of leukemia identified.